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Quotes - Engineering - SalesHeat Exchangers For
Commercial HVAC
Building Heating
Building HVAC duty is characterised by long run hours, modest temperature differences on the water side and a large one wherever steam is involved. Equipment is expected to last decades with minimal attention.
That profile favours a removable U-tube bundle. Free thermal expansion handles the steam differential and the daily cycling, and the bundle withdraws for shell-side cleaning when building water quality eventually leaves a deposit.
Static head matters in tall buildings. Calculate the pressure at the exchanger rather than at the top of the riser, because it frequently exceeds the standard 150 PSI tube-side rating.
Request a QuoteCommercial HVAC Building Heating
What Building Duty Asks For
Reliability over decades, with service that can be carried out during a summer shutdown rather than an emergency. That is an argument for a removable bundle and for clearance in front of the unit to withdraw it, both of which are cheap at design stage and impossible to add later.
It also argues for honest fouling allowances. Building water quality drifts, make-up gets added, and an exchanger sized with no margin will disappoint within a few heating seasons.
Steam Is the Demanding Half
Wherever building steam meets a water circuit, the temperature difference is large and the startup transient is abrupt. That is precisely what U-tube construction absorbs without an expansion joint.
The failure to design against is condensate flooding, which presents exactly like fouling and is far more common on building steam duty than genuine fouling is.
Pressure Before Temperature
In a tall building the static head alone can exceed the standard 150 PSI tube-side rating at the bottom of a riser, before any pump head is added. The HTWU range exists for that case with a 400 PSI tube-side rating.
Check the pressure at the exchanger location. A riser can be comfortably within rating at the top and outside it in the plant room where the unit actually sits.
Potable Water Changes the Selection
Where a boiler or steam circuit heats domestic water, many jurisdictions require double-wall construction. The DSU and DWU ranges cover it, and they are physically larger than their single-wall equivalents for the same duty.
Confirm the requirement with the authority having jurisdiction before ordering rather than at inspection.
What We Need to Size a Building Heat Exchanger
For a steam-to-water converter: the water flow rate, the water inlet and required outlet temperatures, and the steam pressure available at the control valve. Add the allowable water-side pressure drop and the minimum load the unit will have to hold, because turndown is where most building converters actually misbehave.
For a liquid-to-liquid duty: flow rate, inlet temperature and required outlet temperature on both sides, plus the allowable pressure drop on each. Both circuits matter on a liquid duty in a way they do not on steam, and the pressure drop is the figure most often left off an enquiry.
For either: the static head at the exchanger location. In a tall building this is the number that decides whether a standard 150 PSI tube-side rating is adequate or whether the duty needs the 400 PSI HTWU. Calculate it at the plant room rather than at the top of the riser, because that is where the exchanger sits.
And whether the water being heated is potable. If a boiler, steam or glycol circuit is heating domestic water, double-wall construction is frequently required, the unit is physically larger for the same duty, and the single-wall and double-wall ranges are not interchangeable. It is a short conversation before the order and an expensive one at inspection.
